Logical reasoning PrepTest 106 · Section 2 · Question 3

Question prompt

Opponents of allowing triple–trailer Remaining source text redacted.
Why the credited answer is right

Credited answer: B

The notes below walk through why it fits the stem and how to eliminate the rest.

Argument or Facts

Argument

Valid or Flawed

Flawed

Question Type

Weaken Questions

Stimulus Summary

Where triple-trailers are allowed, their accident rate is lower than the national rate for other commercial vehicles, so they’re safer than those other vehicles, and those who say otherwise are wrong.

Answer Anticipation

There are three primary types of logic that dominate the LSAT - causality, comparisons, and conditional logic. When you see an argument that has a conclusion falling into one of these categories, you should focus there. Here, we get a comparative conclusion - triple-trailers are safer than other commercial vehicles. To support this, the argument would need to put forth comparative safety data to allow it to be concluded! Does it do so? Yes, it does - it has comparative safety data. So the flaw must be that this data doesn’t actually show the triple-trailers to be safer. Let’s dig in to see how it falls short. It states that, in the areas where the triple-trailer is allowed, it’s accident rate is lower than the national rate for other types of commercial vehicles. Is that a direct comparison? No, it is not! It takes a look at the accident rate in one area of the country for triple-trailers and compares it to the accident rate everywhere for the other commercial vehicles. That isn’t an apples-to-apples comparison. As such, any answer that makes the data on the triple-trailers in the western part of the country not representative of what it would be nationwide - when the comparison between it and other commercial vehicles would be direct - will weaken this argument. Maybe those roads are wider, or they have a special lane for the triple-trailers that couldn’t be matched in the rest of the country, or they’re less heavily trafficked.

Answer choices

  1. A
    It takes two smaller Remaining source text redacted.
    Why choice A is not credited
    The debate is about safety, not how much they can haul. At best, this answer would suggest that there would be a need for more smaller commercial vehicles, which could lead to more risk of accident, but that would work with the argument, not against it.
  2. B
    Highways in the sparsely Remaining source text redacted.
    Why choice B matches the stem
    This answer brings up a relevant difference between the western highways and the highways nationwide that undermines the safety comparison from the stimulus. If the western highways are much less heavily traveled and thus are far safer, then of course commercial vehicles that only drive there will look safer than ones that drive nationwide, on roads that are much more heavily traveled and thus less safer. In undermining the safety comparison on which the conclusion is based, this answer weakens the argument.
  3. C
    Opponents of the triple Remaining source text redacted.
    Why choice C is not credited
    First, there’s no indication that the twin-trailers are particularly safe, so the opponents could have been right in opposing them! That said, even if they were wrong before, that’s no indication that they’re right or wrong now, so this answer is out of scope. And even if they were wrong before and are thus wrong now, that supports the argument.
  4. D
    In areas where the Remaining source text redacted.
    Why choice D is not credited
    There’s no indication that this wouldn’t also be the case once they’re permitted in other areas (in fact, it supports that view since those areas would then be areas where triple-trailers are permitted), so this answer doesn’t affect the argument. (There’s also no indication that special licenses result in safer driving - they might go to whomever can pay for them.)
  5. E
    For triple trailers the Remaining source text redacted.
    Why choice E is not credited
    This comparison doesn’t play into the conclusion since it’s between triple-trailers in various years, not triple-trailers compared to other commercial vehicles. It’s possible that the rate of fatalities went up for all commercial vehicles during that time period.

What this tests

Question analytics

Based on historical answer selection rates for this question.

Answer choice distribution

  1. A 4%
  2. B Credited 89%
  3. C 0%
  4. D 1%
  5. E 6%

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